Suspensions are used in a variety of different fields for precisely positioning one element relative to another element, wherein one of the elements may be moving relative to the other element. For example, data storage systems use suspensions for positioning transducers relative to storage media.
One type of data storage system is known as a “disc drive”, which uses one or more rigid or flexible discs coated with a magnetizable medium for storing information in a plurality of circular, concentric data tracks. The discs are mounted on a spindle motor, which causes the discs to spin and the surfaces of the discs to pass under respective hydrodynamic (e.g., air) bearing disc head sliders. The sliders carry transducers, which write information to and read information from the disc surface. An actuator mechanism moves the sliders from track to track across the surfaces of the discs under control of electronic circuitry. The actuator mechanism includes a track assessing arm, a suspension and a gimbal for each slider, for example. The suspension includes a load beam, which provides a load force that forces the slider toward the disc surface. The gimbal is positioned between the slider and the load beam, or is integrated in the load beam, to provide a resilient connection that allows the slider to pitch and roll while following the topography of the disc.
As track densities continue to increase, it becomes more difficult for the suspension and control circuitry to position the transducer accurately over a desired data track. As a result, storage capacity may be limited. One factor limiting this precision is relative motion between the transducer and the disc limiting this precision is relative motion between the transducer and the disc caused by disc flutter. Disc flutter is characterized by axial motion of the disc due to dynamic excitation from the driving motor, support bearings, and aerodynamic forces within the drive. These excitations set up resonances within the disc platter(s) which have strong axial/vertical displacement components. This vertical response causes a radial displacement of the concentric data tracks. This radial motion can therefore cause misregistration between the transducer relative to the track during track following operations. U.S. Pat. Nos. 5,999,369 and 6,088,192 discuss some of these vibrational modes and some attempts to reduce track misregistration.
Embodiments of the present invention provide solutions to these and other problems, and offer other advantages over the prior art. However, embodiments of the present invention are not limited by or required to provide these or other solutions or advantages.